Wear Resistance and Surface Roughness of Hybrid Ceramic Crowns Compared to Lithium Disilicate: An In Vitro Study

The surface roughness and wear resistance of restorative materials significantly impact the long-term success of dental crowns. Hybrid ceramics have recently been introduced as alternatives to lithium disilicate, with claims of enhanced mechanical performance and ease of milling.

Twenty extracted human premolars were prepared for full-coverage crowns and randomly divided into two groups (n = 10 each): Group A (hybrid ceramic crowns-Vita Enamic) and Group B (lithium disilicate crowns-IPS e.max CAD). Crowns were fabricated using CAD/CAM technology and cemented with resin-modified glass ionomer cement. Specimens were subjected to thermocycling (10,000 cycles between 5°C and 55°C), followed by a chewing simulator applying 100,000 cycles at 50 N. Surface roughness (Ra) was measured pre- and post-simulation using a 3D profilometer, while wear was evaluated using weight loss and volumetric loss via digital microscopy and software analysis.

Post-simulation, Group A showed a mean surface roughness of 1.45 ± 0.12 µm, while Group B recorded 1.28 ± 0.15 µm. The mean volumetric wear was 0.036 ± 0.005 mm³ for hybrid ceramics and 0.029 ± 0.004 mm³ for lithium disilicate. Both materials exhibited a statistically significant increase in surface roughness after simulation (P < 0.05), but no significant difference was observed between the groups for wear resistance (P > 0.05).

Hybrid ceramic and lithium disilicate crowns demonstrated comparable wear resistance under simulated masticatory forces. However, hybrid ceramics exhibited slightly higher surface roughness post-simulation, suggesting potential for greater plaque retention in clinical settings.